West System Fiberglass Boat Repair & Maintenance Manual

A guide to Fiberglass Boat Repair & Maintenance, Gelcoat Blister Repair and Final Fairing & Finishing with WEST SYSTEM ® Epoxy. 002-550 Fiberglass Boat Repair & Maintenance

WEST SYSTEM, 105 Epoxy Resin, 205 Fast Hardener, 206 Slow Hardener, G/5, G/flex, 410 Microlight and Six10 are registered trademarks of Gougeon Brothers, Inc. Scarffer, 209 Extra Slow Hardener, 207 Special Clear Hardener and 422 Barrier Coat Additive are trademarks of Gougeon Brothers, Inc., Bay City, MI USA. Copyright © 2014 by Gougeon Brothers, Inc. Published by Gougeon Brothers, Inc., Bay City, MI USA. All Rights reserved. No part of the contents of this book may be reproduced or transmitted in any form or by any means without the written permission of the publisher. Printed in the USA. 1st Edition—December 2014 e techniques described in this manual are based on the handling characteristics and physical properties of WEST SYSTEM Epoxy products. Because physical properties of resin systems and epoxy brands vary, using the techniques in this publication with coatings or adhesives other than WEST SYSTEM is not recommended. is manual is updated as products and techniques change. e information presented herein is believed to be reliable as of publication date, but we cannot guarantee its accuracy in light of possible new discoveries. Because Gougeon Brothers, Inc. cannot control the use of its products in customer possession, we do not make any warranty of merchantability or fitness for a particular use or purpose. In no event, shall Gougeon Brothers, Inc. be liable for incidental or consequential damages.

Table of contents 1 Introduction 1.1 Typical ﬁberglass boat construction            1 12 WEST SYSTEM Epoxy for ﬁberglass repair           4 2 Repairing Minor Cracks and Holes 21 Minor crack and abrasion repair             6 3 Repairing Stringers and Floors 31 Reinforcing to improve panel stiffness           8 32 Repairing local core damage              9 33 Stringer repair guidelines               10 34 Replacing active core sections              10 35 Replacing stringers                 11 36 Reinforcing to improve panel stiffness           14 4 Repairing Damaged Skins 41 Assessing and preparing the damaged area          19 42 Backing a repair patch                20 43 Laminating a repair patch               23 5 Repairing Core Related Damage 51 Repairing skin delamination              26 52 Replacing damaged cores               29 53 Repairing transom delamination             31 54 Repairing holed panels                37 6 Repairing and Upgrading Soles and Decks 61 Repairing delaminated soles and decks           40 62 Installing a teak deck                42 7 Installing Hardware 71 Bonding fasteners                 45 72 Bonding fasteners and hardware             46 73 Casting epoxy bases for hardware            50 74 Making fasteners removable              51 75 Removing bonded hardware              51

8 Repairing Keels and Rudders 81 Repairing internal ballast keels             53 82 Repairing external ballast keels             54 83 Repairing a keel hull joint               55 84 Repairing worn rudder bearings             56 9 The Problem of Gelcoat Blisters in Fiberglass Boats 91 Factors affecting blister formation            58 92 WEST SYSTEM Epoxy for repair and coating          61 93 Recommendations for the repair and prevention of gelcoat blisters   63 10 Hull Preparation 101 Evaluating blister damage               64 102 Minor isolated blister damage              65 104 Exposing and removing interlaminate damage         67 105 Special preparations for new boats            68 11 Drying the Laminate 111 How dry is dry?                  69 112 Passive drying                  70 113 Active drying                   70 12 Repairing Blister Damage 121 Minor isolated blister damage              72 122 Extensive blister damage               73 123 Interlaminate damage                74 13 Barrier Coating 131 Preparation                   78 132 Applying the barrier coat               79 133 Bottom paint                   80 134 Recommendations for blister prevention           81 14 Final Fairing 141 Establishing a fair level                83 142 Removing high areas                84 143 Filling low areas                  85 144 Local fairing                   92

15 Finishing 151 Epoxy barrier coating                94 152 Final surface preparation               96 153 Finish coatings                  96 16 Using WEST SYSTEM Epoxy 161 Epoxy safety                  104 162 Epoxy products                 105 163 Handling epoxy                  107 164 Basic techniques                  112 Appendix A Tools                       123 Lofting foil shapes for rudders and keels             126 Cold temperature bonding                 127 Additional reading                   129 Appendix B Estimating guides for WEST SYSTEM products            130 Epoxy handling                    132 Appendix C Applying ﬁberglass overhead                133 Appendix D Repairing machined holes in ﬁberglass laminate           135 Appendix E Problem solving guide                 140 Problem solving notes                 142 Index                       143

Introduction 1 1 Introduction Over the last several decades the popular perception of fiberglass boats is that they are maintenance free and far more durable than the wooden boats that preceded them. While fiberglass boats do, on average, require less maintenance, they are not without problems. In addition to the usual damage from collisions, groundings and the forces of nature, fiberglass boats also suffer from many of the same age related problems of fatigue and moisture that have long been associated with older traditionally built wooden boats. is manual provides repair and maintenance solutions to many of the problems that afflict fiberglass boats. 1.1 Typical fiberglass boat construction A fiberglass boat is a composite structure, made of many layers of various reinforcing fabrics and core materials, bonded together with plastic resins. You could also look at it as a plastic resin shell reinforced with various fibers, or Fiber Reinforced Plastic (FRP). Most loads in the structure are carried by the fibers in the laminate. Resin and core materials support the fibers in positions to effectively carry and spread the loads. Generally, the higher the proportion of fiber to resin in a laminate, the greater its strength and stiffness. e continuity of these resin/fiber skins is critical to the integrity of the structure. It is often necessary to cut through the skin while carrying out repairs, even though the skin itself may not be damaged. Keep in mind that one objective will always be to rebuild for skin continuity to return the load carrying ability of the fibers in the laminate to original or greater strength. 111 Fiberglass resins e vast majority of fiberglass boats in use today are built with polyester resin. Modern unsaturated polyesters used in boat construction are made up of three basic components: glycol, organic acid and reactive diluents (usually styrene). If you were to look at uncured polyester resin at a molecular level, you would see what appear to be thousands of chains made up of alternating glycol and acid units. ese chains are polyester pre-polymers. Adding a peroxide catalyst, typically MEKP, to the polyester resin mixture initiates a cross-linking reaction, that causes the styrene to create bridges, linking adjacent pre- polymer chains together. As the mixture cures, more and more bridges are established, and the free-flowing glycol/acid chains begin to gel, becoming a solid mass. Eventually, enough bridges are built to form a rigid, three-dimensional matrix. e mixture has become a thermoset plastic solid, used in this case, to hold bundles of fibers together in the shape of a boat. 112 Fibers Fibers used in production fiberglass boats take the form of various types of fabrics, including mat (chopped-strand mat), woven cloth and roving, and uni-directional, bi-axial and tri-axial cloth. Each fabric type offers different properties and they are often used in combination to provide specific strength or stiffness properties in different parts of a laminate. Fabric selection may also be based on handling characteristics and cost. Most fabrics are woven or stitched together bundles of individual continuous pultruded fibers of various synthetic plastics. e least expensive and most common fiber used in production boats is E-glass. It is widely available and used extensively for repair. Fibers may also be made of more exotic and expensive materials like aramid or graphite. ese fibers offer much higher strengths as well as higher costs and are used primarily in one-off, high-performance boats where saving weight is worth the higher cost. Stitched fabrics represent a major advancement

2 Introduction in composite technology, by allowing higher fiber-to-resin ratios and stiffer laminates than woven fabrics of equal weight. 113 Cores Cores are used in laminates to increase stiffness of a panel without adding a proportional increase in weight. Doubling a panel’s thickness can result in a panel that is eight times stiffer. By laminating a lightweight core between two fiber/resin skins a lot of stiffness can be gained with a minimum amount of added weight. e skins still take all of the tensile and compressive loads caused by bending the panel but the “I” beam effect produced by the addition of the core allows the panel to withstand much greater bending loads. End-grained balsa is the most widely used core material in production boats. It offers low cost and good impact resistance and compressive strength to resist the collapsing of skins under load. PVC foam cores are available with a variety of characteristics. ey are more expensive than balsa, but more resistant to moisture damage. Honeycomb core is an open corrugated pattern of paper or other thin material on edge. Honeycomb is often used in prefabricated panels for bulkheads and other interior components. 114 Construction methods Generally, production fiberglass boat hulls are built in a female mold. A release agent is first applied to the surface of the mold, over which the gelcoat material is applied. Gelcoat is usually a pigmented, unsaturated polyester resin and may be anywhere from 12 to 22 mils thick. It is designed to act as a moisture barrier for the underlying laminate, as well as to provide a smooth, glossy, cosmetic finish. Subsequent layers of fabric are saturated with resin and laid up over the gelcoat. ere are as many lay-up schedules as there are boats. A typical hull section might consist of the layer of gelcoat, several alternating layers of mat and woven roving, and in many cases a core material such as end grain balsa or foam, followed by several more alternating layers of saturated mat and woven roving (Figures 1-1 and 1-2). Hull thickness may vary from boat to boat. Older boats were often laid up with a solid glass laminate thickness of 1 ½" (3.8 cm) to as much as 5" (12.7 cm) in the keel areas of the more heavily-built boats. Today, however, the trend is toward thinner, lighter laminates, making the structural integrity of each of the laminate components all the more critical. Standard lay-up relies on gravity to hold all of the resin saturated material in place until cured. e technique of vacuum bag laminating has advanced composite construction by allowing the builder to compress the entire wet-out laminate evenly in the mold, and more accurately control the resin content and the strength-to-weight ratio of the laminate. Although it’s not often associated with fiberglass boats, wood is used extensively in fiberglass boat construction for primary and secondary structural members like bulkheads, frames and stringers, core material, blocking and trim. Stringers, bulkheads and other Figure 1-1 Typical solid (single skin) fiberglass laminate. Various reinforcing fabrics are bonded together with polyester resin. Figure 1-2 A typical cored laminate consists of end-grained balsa or other core material sandwiched between two resin/fiber skins. Gelcoat Gelcoat Outer skin– Alternating mat and roving Inner skin– Alternating mat and roving Core material Alternating layers of mat and woven roving

Introduction 3 interior fixtures are bonded in after the shell is laid up. Many fiberglass boat repairs involve wood and the problems associated with using polyester resins to bond to wood. Terminology used to describe the structure of fiberglass boats is not always the same terminology used to describe wooden boats. Where fiberglass boat components serve the same functions as wooden boat components, their names are often the same. However, materials, and manufacturing methods vary from small boat to large boat, from power to sail and from manufacturer to manufacturer. Here is a general guide to the fiberglass boat terminology used in this manual (Figure 1-3). 115 Hydrolysis and gelcoat blisters e repair procedures in this manual address problems most often associated with mechanical damage–abrasion, bending, fatigue, impacts and the resulting water damage to cores or other structural components. Another type of damage common to fiberglass boats is chemical in nature. Hydrolysis (and its symptom, gelcoat blisters) is a widespread and growing problem in the fiberglass boat world. Hydrolysis is more than a cosmetic problem. When water soluble materials in a polyester resin laminate mix with moisture that has penetrated the laminate it creates an acidic fluid. e fluid collects in cavities under the gelcoat layer to form blisters. is acidic mixture also attacks the polyester resin, severing the chemical bonds that hold the resin matrix together, as well as the resin to fiber bonds. Once hydrolysis has started in a polyester hull, the hull’s strength has been compromised and the potential for serious additional hydrolysis will never go away. If you own a fiberglass boat built with polyester resin, you should be aware that the potential for this problem is high, especially in warmer climates. Any damage due to hydrolysis should be included in an assessment of a boat’s condition before repairs are made. Hydrolysis and gelcoat blisters can be treated with WEST SYSTEM Epoxy to limit further damage and in many cases restore a hull’s structural integrity. For more information about hydrolysis and gelcoat blisters refer to Section 9. Figure 1-3 Components of typical fiberglass sail and power boats Bulkhead Bulkhead Cabin top Toe rail Rub rail Rub rail Cabin liner Keel (external ballast) Stringer Chine Keel Strake Floor Stringer Keel bolt Keel boss Cabin sole Cockpit sole Tabbing Hull (cored laminate) Hull (solid laminate) Deck Deck

4 Introduction 12 WEST SYSTEM Epoxy for fiberglass repair Unsaturated polyester resins perform fairly well during the construction of a structure when all of the layers of resin are applied and allowed to cure together. is type of bond is considered a primary bond. Problems can occur, however, when you try to bond polyester resin to a previously cured laminate as is necessary in every repair application. is type of bond is secondary or post-bonding. To effectively repair damage typical of fiberglass boats, the repair material must be a superior structural adhesive, capable of bonding not only to polyester resin, but also to glass fiber, wood, metal and other materials. ere are several important reasons to use WEST SYSTEM Epoxy rather than a polyester resin or other material for fiberglass boat repair. Polyester resin can shrink from 5% to 8%, creating stress concentrations at the repair joint wheras epoxy doesn’t shrink. In addition, epoxy is more effective as a moisture barrier and it forms a superior mechanical bond with the cured polyester and other materials in secondary bonding. Since epoxy is more durable than polyester, the epoxy repair actually may be stronger than the original structure. When you consider ease and practicality of application, availability, safety and access to technical assistance, WEST SYSTEM Epoxy is an excellent choice for fiberglass boat repair. 121 Using this manual Study and become familiar with all of the steps in a procedure before beginning a repair. e procedures described in this manual assume a working knowledge of WEST SYSTEM products and the basic techniques of epoxy use. If you are unfamiliar with or have any questions about the application and handling techniques of WEST SYSTEM Epoxy products, read Section 16–Using WEST SYSTEM Epoxy thoroughly before proceeding with repairs. e WEST SYSTEM User Manual & Product Guide also provides basic epoxy handling information as well as complete current product descriptions and selection and coverage information. It is a free publication available through WEST SYSTEM dealers and/ or can be downloaded at westsystem.com. Some fiberglass repair procedures can be hazardous. Always wear appropriate eye protection, skin protection and a dust mask when cutting or grinding fiberglass. Follow safety guidelines when handling epoxy (Section 16.1). If you have additional questions after reading the Using WEST SYSTEM Epoxy section, contact the WEST SYSTEM technical staff: WEST SYSTEM P.O. Box 665 Bay City, MI 48707 866-937-8797 (8:00 AM-5:00 PM EST) technical@gougeon.com westsystem.com

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West System Fiberglass Boat Repair & Maintenance Manual

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